Over recent years, RFID has become an increasing function of providing wireless communications. For example, RFID is commonly implemented in security devices (e.g., swipers and/or card readers) for businesses as well as in many other areas. Unfortunately, RFID is typically passive and has its range limited by distance and physical obstacles. Moreover, RFID reader power is limited by regulation, which causes range issues since RFID operational range is constrained by the available power. As such, RFID reliability and responsiveness are commonly compromised in practical environments. In view of the foregoing, there exists a need to extend RFID range within the given power limit while still remaining as a passive RFID. The related art has failed to provide such functionality, including those references listed below:
U.S. Pat. No. 7,786,868 discloses an RFID device with multiple passive operation modes that are fully passive or boosted passive. The boosted passive mode utilizes an internal energy booster. The energy booster may include a one-port transistor and an energy source that is used to power the transistor.
U.S. Pat. No. 7,443,299 discloses an extended range RFID system for discs such as CDs, DVDs, or minidiscs. A special RFID transponder and antenna configuration is used and antenna elements are coupled to the transponder extending in opposite directions across an outer annular zone. The monopole or dipole mode of antenna operation (utilizing a metalized disc layer) results from this antenna configuration and is stated as “to more than double the range of the system”.
U.S. Pat. No. 7,374,105 discloses an RFID tag having an RFID integrated circuit and an antenna that are combined with a first passive antenna circuit to provide an extended operating range. The second passive antenna circuit is essentially identical to the first antenna, only it has larger dimensions, and is positioned with the coil of the second passive antenna circuit surrounding the first coil to extend the operating range.
U.S. Patent Application 20090289773 discloses a method for extending the read range of passive RFID tags. Excess excitation energy is dissipated through circuitry for a constant current power supply that is implemented either with discrete components integrated into the ASIC design, a network that minimizes the amount of energy that is converted to heat by a traditional configuration's shunt regulator, and/or a sleep mode for reducing the energy consumed by an RFID tag after it has been read.
U.S. Patent Application 20090085750 discloses an extended RFID tag. The extended range RFID tag includes a UHF RFID tag having a dipole antenna attached to a surface of a substrate and further includes an antenna extension that overlaps a portion of the dipole antenna for electromagnetically coupling the antenna extension and the dipole antenna when in operation.
U.S. Patent Application 20070285244 discloses a long range RFID transponder. The improved range is achieved through the RFID power generation's Passive Magnetostrictive Electroactive device component. One example includes a passive magnetic field sensor made of layers of Terfenol-D magnetostrictive material and ceramic PXT-5 to act as a generator to power the RFID when in range of the querying transceiver magnetic field.
U.S. Pat. No. 7,659,821 discloses a smart RFID infrastructure and method that enables communication between RFID tags. Information tables from individual RFID tags are aggregated into master information tables on writeable RFID tags.
U.S. Pat. No. 7,515,049 discloses an extended read range RFID system. This system utilizes an apparatus to extend the reader's antenna signal to a location proximate to the RFID tag. In another embodiment, the apparatus utilizes at least one magnetic rod to create a magnetic path for the RF field to travel between the reader's antenna and the RFID tag.
U.S. Patent Application 20100201488 discloses a system for displaying read range of a RFID reader based upon feedback from fixed RFID beacon tags. An interrogation signal is transmitted from the RFID reader to these fixed RFID beacon tags at known locations.
U.S. Patent Application 20060202032 discloses an automatic identification and data capture system.
Among other things, none of these references teach a strong passive ad-hoc RFID network whereby RFID tags can store energy or data, and/or (wirelessly) couple to and communicate with one another.